Simulation of an on‐board hierarchical multistage digital FDM demultiplexer for mobile scpc satellite communications
Helmut Eyssele, Heinz G. Göckler · International Journal of Satellite Communications · 1990
Abstract This paper is focused on the finite‐precision time‐domain simulation of the hierarchical multistage method detailed in References 1 and 2 for demultiplexing of an FDM signal being composed ofL= 32 slot signals. This approach to FDM demultiplexing is based on the processing of complex signals by linear‐phase FIR filters, where at any stage of processing the respective signals are always oversampled by a factor of two. The simulation results fully confirm the system performance predicted in Reference 1 by modelling the distortions (spectral foldover and quantization noise) inherent in the system: assuming an ideal FDM signal at the input port of the analogue anti‐aliasing bandpass filter in front of the analogue‐to‐digital converter, a minimum signal‐to‐distortion ratio (S/D) of 30 dB is achieved at allLoutput ports of the demultiplexer with {w,wF,wi} = {11,12,14}, as anticipated in Reference 1. The signal word lengthwapply to the A/D conversion,wFto requantization between the filter stages, andwito filter internal signal processing.